N I V I   blog



Greasemonkey will blow up business models (as well as your mind)

May 8, 2005

Greasemonkey is a Firefox extension which lets users add “user scripts” (DHTML, technically) to any web page. These scripts can change any aspect of a web page’s behaviour, interaction, or design. This little baby is going to blow up business models. Let’s look at some examples.

The right metaphor

Greasemonkey lets you mash-up websites. It lets you extend and script websites and integrate that script right into the original site as if the designers had intended it to be there. It lets you use their web site, their data, their servers, their work to serve your purpose and function. There will soon be an army of hackers enhancing every site you use. Whether that site likes it or not.

I am still struggling to find the right metaphor to describe the power of Greasemonkey. Here’s a try:

Greasemonkey is to websites what inheritance is to objects in object-oriented programming.

Object-oriented inheritance lets programmers re-purpose and extend the functionality of existing programs. Programmers can build powerful new programs very quickly with inheritance. The most advanced operating system in the world earned that title for a reason. The inheritance metaphor is probably accurate — but not very appealing to the layman. Here’s another try:

Greasemonkey is to the deep web what hypertext is to documents.

Hypertext allows us to connect specific text in one document to text in another document. Greasemonkey allows us to connect a page from the deep web to another page on the deep web. Deep web pages are created dynamically from database queries. So, Greasemonkey is, in a sense, hypertext for databases.


First, browsers that don’t support Greasemonkey are going to lose marketshare as “must-have” Greasemonkey scripts roll out.

Second, someone is going to get sued. How happy is Netflix going to be when I use their site to download TV shows from BitTorrent trackers? And how are they going to stop me? Sue the guy that made the Greasemonkey script? Block my IP address from using Netflix?

Third, there will be those who embrace the competition that Greasemonkey is going to bring to their business model. They will use Greasemonkey to enhance the strength of their brand and increase marketshare. Companies like Amazon who have open APIs come to mind.

Fourth, Greasemonkey will have to be designed to scale. Right now, to use Greasemonkey

  1. You need to install Firefox. We need Greasemonkey across all the major browsers.

  2. You need to install the Greasemonkey extension. This isn’t too hard but already there is a Greasemonkey compiler that can compile a script into a stand-alone Firefox extension. With this compiler, script designers won’t have to tell their customers that they need to install Greasemonkey anymore.

  3. You need to install the specific script you want to use. This doesn’t scale well. Greasemonkey could be modified to ping a clearinghouse for scripts that are relevant to the site you’re on. Perhaps with UDDI.

In summary

Greasemonkey: This isn’t your dad’s http.

See also: Jon Udell’s Greasemonkey screencast, Greasemonkey etiquette

Note: If you liked this article, check out the rest of my blog.

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Comments so far:
  1. User scripting blows up business models

    Babak Nivi on why user scripting will change the web. Of course, this applies as much to Opera User JavaScript as it does to Greasemonkey.


  3. This is amazing and sure going change the market dynamics its just the start of web 2.0


  5. Greasemonkey will allow you to redecorate your shopping mall to your wishes, whenever you walk in, without permission of the owners.

    Out goes the awful music!

    Mark Wubben

  7. Greasemonkey

    There’s a new extension for Firefox that is quickly becoming interesting. It essentially allows users to add functionality to other…

    Gen Kanai weblog

  9. > These scripts can change any aspect of a web page’s
    > behaviour, interaction, or design. This little
    > baby is going to blow up business model

    The arms race is in full effect:



  11. Opera version 8.0 supports user Javascript files. It should theoretically be able to use Greasemonkey scripts, but those that I have tried (gmail search and lickr) produce errors in the Javascript console.

    Here’s a guide to user Javascript:


  13. Good insights, I agree with most of what has been said here. The metaphor “Greasemonkey is to websites what inheritance is to objects in object-oriented programming. is not very fitting, since in OOP the object’s class defines, how the object could be inherited, while with GM you just patch the object any imaginable way.

    The clearinghouse idea looks promising!


  15. Grappling with Greasemonkey

    Sam Ruby

  17. 1) Proxomitron could already do that and more. So technically the idea isn’t new.
    2) Of course, usability matters. I don’t really use Firefox, so I won’t bother trying it (but I believe that GM may be more user-friendly than Proxomitron). I suspect that pretty much the same thing can be done with my Opera (it can run user JS on every page), though.
    3) It is indeed very likely that it will become popular in the future, at least among the digital “haves”. It clearly has some potential and will help us last until the Semantic Web comes along.


  19. Check out the Expedia Expanded Search. It is great if you want to fly but are very flexible.

    Jesse Andrews

  21. You need to install Firefox. We need Greasemonkey across all the major browsers.

    This is not strictly true: Many Greasemonkey scripts will work in Opera: Stay away from XSLT, XPath and Mozilla-specific extensions, and you should mostly be able to run your GM scripts in Opera.

    Opera’s User JavaScript on the other hand will not always run in Greasemonkey, since it has the possibility of intervening in more places than GM has. An example of this is Plainscript.

    As for your 2), Opera’s User JavaScript implementation is integrated into your browser: All you have to do is to point Opera at your User JS directory.

    As for your 3) — there are two script repositories on the way, my userjs.org which will focus on Opera User JavaScript, and Jeremy Dunck’s userscript.org.

    I am thinking that autodiscovery of site-specific user scripts is best handled with, you guessed it, a user javascript. Probably easiest achived by using a minimal, custom API.

    Arve Bersvendsen

  23. Greasemonkeyed!

    Babak Nivi posts this great explainer why Greasemonkey is changing the rules of the Web. [via Sam] My predictions of the impact on online business models: Advertisement - Greasemonkey is to online advertisement what TiVo to TV advertisement. In…

    Alexis Smirnov

  25. That is crazy. If it catches on it could have powerful implications for many online businesses. It is always fun to see how people are changing what they see online to make life easier, even though most of the time it is not what companies wants us to do.

    Ookami Snow

  27. here’s another metaphor:

    “Greasemonkey is to Firefox what ActiveX is to Internet Explorer”

    Or in other words, a malicious greasemonkey script can do serious damage.


  29. Is Greasemonkey the same as Claria (Gator)?

    A post over on Nivi got me thinking if Greasemonkey is a good thing. I can see the obvious benefits as a user having the ability to add

    76 | Ideas

  31. links for 2005-05-09

    Tacky Living (tags: crafty) palestine (tags: blogs political) 15 things you can do with RSS (it was supposed to be 10, but I got carried away) - Tim Yang’s Geek Blog (tags: web technology) How to detect lies - body language, reactions, speech pattern…


  33. Firefox Extension Greasemonkey, will blow up business models (as well as your mind)

    Firefox Extension Greasemonkey, will blow up business models (as well as your mind)…

    Grubbykid.com :: Links

  35. Nice overview…even cooler that you managed to sneak Philip K. Dick in an Amazon screenshot!


  37. Of note, greasemonkey isn’t a firefox only thing. Opera 8 has it too, they call it user javascript, but they also have a greasemonkey compatibility mode.

    Peter Tripp

  39. I hear Gm also cooks up a great plate of Green Eggs and Spam, as well.

    Will wonderments never cease?

    You might want to “amend / append” item #2, because I think it reads and/or implies that you don’t need to install all/each of the compiled GmScript-extensions, which you do, so, it’s not really that much different, altho I think I get your intended meaning. Perhaps a trailing parenthetical comment:

    (though you would need to separately install each compiled GmScript extension, of course)

    Am I picking nits? Depends on the reader and their level of understanding of FF and extensions.

    Good, interesting article, though. Makes one think and consider and all that jazz.

    Bill Donnelly

  41. Nomenclature suggestion

    I think individual user scripts for Greasemonkey should be called “Smart Tags”. Everyone who switched sides on this one since 2001, please raise your hand. (For once, I get to smugly be consistent on this one.)…

    Anil Dash

  43. Jeebus man, take a few slow, deep breaths… you sound like you’re talking about a world-changing invention like the Segway or something.


  45. […] #183; Filed under mac, windows, linux, programs, interesting article Nivi : Greasemonkey will blow up business models (as well as your mind) To th […]


  47. Monkeying Around with Web Business Models

    Babak Nivi: “Greasemonkey will blow up business models (as well as your mind)”. I’m not particularly sure that I want my mind blown up, but any attempt to answer the thorny “what does it all mean?” question is certainly to be welcomed.


    Peer Pressure

  49. Greasemonkey is just the beginning of user-modified web pages.
    My master’s project, Outfoxed, adds commentaries and re-orders search results, hilights dangerous links, alerts you to bad business practices, and certifies the authenticity of files, all using the user’s individual social network. I’m looking for beta-testers, so please give it a look!


  51. Go, Greasemonkey, Go!

    Perfect is in the eyes of the beholder. Even though Seth is talking about a billboard in Grand Central, many of businesses with websites will be stumbling and ch


  53. […] e owners no longer have control. And ofcourse, not everybody likes change. Take a look at this post by nivi, and you can see why. You would now be able to lookup an Ama […]


  55. What things look like on my side of the new digital divide, or hacking Amazon for fun.

    That’s nice, but not all that spectacular. Yet I expect that the first GreaseMonkey script to screenscrape this information off of Amazon and use it within some other site is already in the process of being written. And maybe Amazon will never …

    Just Imagine...

  57. […] tial is noted … in addition to my old posts here , there and there … see this nice summary … some comments are elaborating on … Greasemonkey is […]


  59. So what are these business models being blown up?

    Showing competitor’s book prices on Amazon? Book Burro uses Amazon’s own API. Amazon gives away that information for repurposing intentionally. I can’t seem them being taken by surprise.

    Greasemonkey isn’t introducing any new competition. It’s making it slightly easier to see what the competition is (assuming that Bittorrent competes with Netflix, and libraries with Amazon, which certainly isn’t clear to me), but it’s making it slightly easier than checking in another window.

    Minor gains in convenience are great, but they’re still minor gains in convenience, and there is a vast difference between making something more convenient and revolutionizing online business.


  61. This “baby” just blows.

    “These scripts can change any aspect of a web page’s behaviour, interaction, or design. This little baby is going to blow up business models.”

    Is this what happens when a developer gets bored? This is just what already badly designed web sites need…letting the “user” change the way it looks and interacts.

    We’re going back in time, just to have the ability to do some cool new trick.

    Design and usability should be left to the professionals. But, I suppose if they did their job in the first place, we wouldnt have silly little scripts like this at all.


  63. Two comments on people’s comments…

    First, a malicious greasemonkey script can blow up your browser, yes, but that’s true of any Firefox extension. The fact that you have to explicitly add scripts is a feature, not a flaw.

    Second, “design and usability should be left to the professionals”? Like hell, design and usability should be left to the user. Let the user and his browser display what they want to display… they will anyway… and follow Google’s first and most successful site in just providing the content in as plain a way as possible, and get out of the way. Play “what if”… “what if” your site was an RSS feed, would it be better off with glowing shadowed shuffle-down menus or simple markup that works with all the bells and whistles left to the end-user?

    Peter da Silva

  65. Client power: you modified the page your browser receives (greasemonkey)

    GreaseMonkey is an extension for Firefox browser that easily allows you to change the rendering of a web page received by your browser. The example image shows how Greasemonkey can insert prices from competitive booksellers right into Amazon.. Well, yo…

    Paolo Massa Blog

  67. Nivi : Greasemonkey will blow up business models (as well as your mind)

    Nivi : Greasemonkey will blow up business models (as well as your mind)
    It lets you use their web site, their data, their servers, their work to serve your purpose and function. There will soon be an army of hackers enhancing every site you use. Wheth…

    house of the hanged man

  69. Nivi : Greasemonkey will blow up business models (as well as your mind)

    Greasemonkey - a fancy firefox plugin…

    Daily Links

  71. I’t ’s interesting to note that nothing is in fact really new (from my own post on greasemonkey):

    * bookmarklets have been arround for some time, and already led to amazing applications, such as when you combine Google Maps with other data sources, such as users’ pictures and annotations.
    * nothing new either about the concept of “Web annotation”, think of the WikiAlong Firefox plugin, letting you annotate webpages (on the public WikiAlong Wiki or an a private, company or project group wiki).
    * The really new thing with Greasemonkey is the ease scripts can be written (javascript has been around for almost 10 years), made available (simply put a file online) installed (right-click), and propagated (think of a user script showing the available user scripts for the site you’re browsing!!). Without any doubt, zillions of these scriptlets will be hacked together and spread like wildfire, extending and bending existing functionality. (see for example Greasemonkey for Google Maps)

    Pascal Van Hecke

  73. Another example of greasemonkey making money and serving a purpose: Amazon Localization User Script

    Pete Freitag

  75. Outfoxed

    Outfoxed: I was following a discussion about how the Greasemonkey extension to Firefox will destroy many existing business models, when I saw a link to this master’s project on applying metadata to existing webpages by readers and their friends… bas…

    JD on MX

  77. Design and usability should be left to the user? YEAH RIGHT!

    Most users want ease-of-use, and clear design when they get there…they dont want to do that themselves.

    If we all followed Googles “wonderful” plain design, we might as well be back in 1995. That’s nuts.

    Design it plain, and then get out of the way? Yeah, only if I want to bore a user to death…or just really piss them off.

    We can have cool developer “goodies” without having to foresake design. This isnt one of those cases.


  79. This line of discussion intrigues me, although I can’t say I understand all of it. Nor do I want _my_ mind blown up, either.

    My professional background is in technical editing. I am more of an early adopter than a techie. But this Greasemonkey stuff has really started me thinking.
    Clear and concise writing is one casualty of blogging and what used to be called internet time. People like me know how to bring out a writer’s voice by following Strunk and White’s famous dictum, “Omit needless words.” I have wondered for a long time how basic editing principles could be brought to bear most effectively on the net. Perhaps Webmonkey or Java scripts could provide the answer.
    If anyone wants to try this out, I would be willing to do some editing _pro bono_. A good testing setup would be something like this:
    1. I am notified of a request to edit a certain text to a certain level of edit (e.g., correcting major mistakes, correcting punctuation, cleaning up grammar, flagging unclear passages, doing everything—I know of some excellent checklists that could be used).
    2. I click to accept the assignment and am taken to a page with the original text and some sort of overlay (perhaps similar to that used by Book Burro). One important thing the overlay does is to let me correct the text without having to correct—or even know—the underlying code.
    3. I enter my edits such that all revisions are evident (all major word processing programs provide for this). Other WP tools (ported from Open Office?) such as spellcheck would also be helpful.
    4. The author gives me feedback of what edits were accepted, reasons why or why not, statements of eternal gratitude, offers of first-born sons, etc.
    What think, O Wise Ones?
    “I am sorry this is so long. I did not have time to make it short.”

    Hyphena Tor

  81. If GreaseMonkey is like having your own well stocked garage, Proxomitron is like having a flying carpet.


  83. Web 2.0 Weekly Wrap-up, 9-15 May 2005

    This week: Greasemonkey mayhem, Ajax fever, Web Design Minimalism mojo, Blogpoly Fun!, Yahoo
    Music Engine rave…

    Read/Write Web

  85. What You Say Or Do Doesn’t Hurt Me

    hey all. Long weekend. Went to the Pacers game Friday with my brother. That rocked. They won.

    Went to the Pacers game Sunday with Kelly. That sucked. They lost. (And there was a whole row of the most obnoxious, immature and insanely STUPID Pistons f…

    X-Tra Rant


    Thinking that people do change everything around, replacing names with random strings, trademarks with anything. Evil guys can install scripts without knowledge of the browser user, browsers in public library being modified, ….

    Worse then that, not only the browser can change contents, ISP can certain does that, routers can do that, and every things being pass through the network is subject to change without notice.

    Of cause, without Greasmonkey, everything can be done that way. It just make that easier. However, we are facing that dead of trust. Trust no more. Nothing can be sure any more. The web is useless.


  89. It is not such a big deal. And when the web site changes its page? Sigh. The toys people are impressed with …


  91. Where is this technology taking us? This and the open source applications are taking us to an ‘era’ of “Power to the People”. Large corporations are losing out their rights on Intellectual Properties, not to people who steal them, but to people who say they have no use for them anymore. Interesting development, I should say.

    Venkat Mangudi

  93. Greasy CLiki

    Since Greasemonkey is so cool and is revolutionizing the web (get in line), I figured I should play with it. Also I thought it would help me to know a little Javascript when the Dashboard, Ajax and Greasemonkey people…


  95. Grease Monkey - Its your browser

    Have you ever wished that all links into New York Times pages were links into the single-page format ? Or that web-based Google Mail “auto-saved” mails regularly to safeguard against sudden network outage or laptop power failure ?

    Well now you …

    Sumedh Mungee

  97. I wonder what, if any, impact the IBM decision to recommend firefox to all 130,000 employees will have on “greasemonkeyworld?” Granted, 130,000 people is now a drop in the bucket when it comes to the overall Firefox footprint. But combined with the fact that they are at IBM and they are also all supposed to be blogging…not that GM scripts need any help building momentum.


    John Franklin

  99. Hrm, the comment form ate half my comment. (after opening angle bracket).

    Wow, I am amazed at the people that are downtalking the importance of Greasemonkey/Opera Userscripts. Ironic that you are doing so in a _Weblog_. Which from a technological POV is even a lot older than the possibility of userscripting. Increasing the usability of a task can make all the difference between something you do and something you don’t do.


  101. Productivity / Geeky crappy stuffy

    Geeky Stuff: Why adsense for feeds is a bad idea (at least for now). Matt Haughey makes some very good arguments for not putting ads into RSS feeds for now. WinAmp Plugin for the iPod. About time this came about….


  103. In love with Platypus and Greasemonkey

    Greasemonkey is a Firefox extension that lets you rewrite arbitrary web pages client side from your browser by installing “user scripts” that get injected into the page. As you may or may not have realised Greasemonkey has the potential to…


  105. Greasemonkey will blow up business models (as well as your mind)

    Greasemonkey will blow…


  107. GreaseMonkey is the real Semantic Web (and now works on HospitalityClub)

    GreaseMonkey is an extension for Firefox that allows you to totally (and easily) change the layout of any received web page. Don’t like the color of the banner of that_site.com? You can change it! Do you prefer to have the…

    Paolo Massa Blog

    you dont have a right to change a page layout that ISNT YOURS! If you 15-years-old script kiddies dont like my site, so fuck off! What next, steal cc passwords because “information should be free”??? HOLY SHIT!!!! But you’ll get caught, sooner or later…


  111. bookburro.org has the latest version of the book burro extension. It currently adds caching, abebooks, and powell books.

    Jesse Andrews

  113. Yes, GM will force feckless site designers to develop a functional business model. Forcing me to waste my surfing bandwidth and sacrafice my privacy to ad networks is NOT a “business model”; it’s sloth. If siteA actually had content “worth” something they would sell it — perhaps charge a subscription. Why don’t more sites do this? Because they know right well nearly no one will pay them for “their” “content”. Those that can do. Those that can’t foolishly call embedding ads a business model.

    GM brings the power of geeks to the average guy. GM ought not be considered a nefarious tool of net denizens anymore than a hammer should be. The contrary is the tired, fallacious argument in favor of attempting to supress my constitutional right to keep and bear arms. It doesn’t work there and it’s not going to work against freedom to tinker with GM.


  115. Remember you do NOT have the right to not-look-at every single ad on my site. You waive your personal liberties when you surf to my domain. It’s our implicit, unratified contract. Not obeying my wishes is itself punishable by death. Please enjoy my site. GM automates your ability to do as you please — something we’ve already established you don’t have the right to do. Bow before me!

    Vogon geek

  117. Not wanting to sound like a broken record, but this “feature” has been available sine the dawn of java script debugging and DOM model exposure by IE.
    As somebody pointed out Meta Tags and Proxomitron has been around for a while.
    Don’t get me wrong, I appriciate the enthusiasm with which this article has been written. Obviously the author l.o.v.e.d the concept.
    In any case, greasemonkey is here to stay .. hmmm .. how about scripts which change the amount posted for submissions to payment gateways :p this has been possible since the release of Visual InterDev v0.1 .. hows that for business model shake up :D


  119. I know it’s an old post, but….

    You need to install the Greasemonkey extension. This isn’t too hard but already there is a Greasemonkey compiler that can compile a script into a stand-alone Firefox extension. With this compiler, script designers won’t have to tell their customers that they need to install Greasemonkey anymore.

    Sorry, but this is totally pointless. The point in GreaseMonkey is that you don’t have to install an extension. Thus you don’t have to restart the browser, you don’t have to revisit the page that made you look for a user script. That’s (almost all) what greasemonkey does. Otherwise the same (and more) can be accomplished with extensions (and this is the way it has been done).

    But it also forces the developer to create an XPI (with separate FireFox and Seamonkey install scripts/manifests) which is just too much of a barrier for simple things. Of course the ‘compiler’ that you were talking about is a nice thing to have (I wanted to create something like that for myself) beause some users might not see the point in installing greasemonkey and then a usersript. At least at first :). So it may be wise to publish your usersripts as extensions as well. But not instead of the original form.

    Laszlo Marai

  121. Unless I’m quite mistaken, the recent versions of Greasemonkey disable off-server requests… the feature that enables all of the coolest GMs.

    You can still put into links to off-site, but you can’t hit a remote XML-RPC to fetch a price.

    Mike Purvis

  123. “Design and usability should be left to the professionals. But, I suppose if they did their job in the first place, we wouldnt have silly little scripts like this at all.”

    Exactly. Whenever I get frustrated by a usability type of issue on a major web site (like the inability to sort by negative feedback on eBay…), I take a quick look to see if there’s a GreaseMonkey script that fixes it, and most of the time, there is.

    If I were in charge of re-designing a major Web site, I’d take a look at what available GreaseMonkey scripts were out there, and build the ones that made sense into the site itself.

    Al Chumley

  125. GreaseMonkey, gm4ie and others makes internet much more flexible and free, now you dont have to tolerate anything annoying on any web and the end-user can choose how is the service.


  127. It’s been a year and a half since this article. Any new thoughts, Nivi? Anyone?


  129. Nivi, what do you think of iMacros?

    Al Meir

  131. You don’t change the site at the site’s server. You change a already loaded copy of the site locally! No matter, if you use Greasemonkey or you don’t using it: the traffic will be the same.


  133. Dirk,

    actually you do, the web page loads just the html, it doesn’t load the images, or advertisements. so if were to strip out those parts of the html at this point they wouldn’t get loaded, thus no bandwidth would be wasted for loading them.

    However much to the dismay of advertisers i COULD load the advertisement, but not show it to myself. That would bring in shown advert notification to them and money to my favorite site. BUT i wouldn’t see the ad, on need to wait for it to load before rendering. So what i do is a waste the bandwidth when it does not disturb me, and the advertisement way just no longer works


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  • About Me
  • I am currently the CEO of Venture Hacks, an EIR at Atlas Venture and an Advisor to Songbird and Grockit. I live in San Francisco. More >
    nivi at alum.mit.edu
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